Method and apparatus for testing



` May 23, 1944.

M. KNoBEL. :lz-i- AL vMETHOD AND APPARATUS FOR TESTING Filed Oqt. 28, 1940 2 Sheets-Sheet lt .M KNOBEI. ETAL 2,349,736

METHOD AND APPARATUS FOR TESTING I Filed oct. 2a'. 1940 zsneetsheerg May 23, 1944.

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Jo/"mv Dickson BY John Z1. ayrm'ier7 ATTORNEYS Patented May 23, 1944 Max Knobel, Arlington, John B; Dickson, Northhampton and John W. Baymiller, Chicopee, Mass., assignors to A..G. Spalding. & Bros. Inc., Chicopee, Mass., a corporation of Delaware` Application octob'erfzs, 1940, serial No. 363,130

21 claims.

This invention relates tov processes and machines for testing, and particularly for` testing the dynamic balance of golf clubs and other sporting goods;`and, to the electrical measurement of such testing.

Although the present process and apparatus@ has awide variety of uses, as willbe readily appreciated, for convenience it is illustrated land described herein for the testing and matching of golf clubs.

In order to attain a low score, or even 'toderivel a reasonable satisfaction from the game of golf, an individual player should have a set of clubs, each one of which possesses affeel that that individual happens to like. A matched 4set of golf clubs is highly desirable. a v

Heretofore it has not beenpossible to accurately match clubs, and the players havecomplained that the feel of several of the clubs Yof a supposedly matched set was not satisfactory. These failures have resulted in spite of the efforts' of the golf club manufacturers to carefully match clubs. Numerous tests adapted to indicate the balance of the club have been tried corn-` mercially. ,All have involved determining the,l leverage weight, .or in other words all have involved a static balance test. Although a dynamic balance test for some playing implementshas been proposed, it has not been used commercially. The latter` proposed dynamic balance test has been considered to be impracticable forthe manufacturing process becauseof the great amount of time and skill required for accuratelymaking each test. No golf club dynamic balance testing machine detecting diierences in the feel factor of rigid shafted clubs and of whippy shafted clubsv has heretofore been available.

In the making of high quality clubs, such as those in registered or matched sets, the aim has been to keep such records that if; a clubwere lost or `broken and aplayer wished to replace it,a club having an identical head weight and other factors could be produced. To achieve this, it has been necessary to keep detailed records on each `of a number of manufacturing operations because it was recognized that the leverage weight test was not a completely satisfactory test of the feel factor.

The present invention improves upon the usual matched sets by adding and insuring a substantially identical feel factor to` a set of clubs.

It is an important object Vof the present invention to provide a method of testing golf clubsto accurately and simply measure the feel factor.

Other objects are:

To provide ,a golf club testing process and machine providing a `commercially feasibledynamic balance test. a

To provide a machine adapted to automatically measure the period of an oscillating member.`

To provide'a machine affording a convenient method of vmeasuring the moment of inertia of Va body.

To provide lan electrical measuring device conveniently and accurately measuring a predetermined group of electricalimpulses.

In accomplishing the aforementioned objects anduother objects apparent from areading of `the specification, use is made of several features, among the most important of which are: e a The use of counting mechanism controlling a -switchvto close an electrical circuit after a predetermined number of impulses and to reopen the electrical circuit `after a predetermined additional `number ofimpulses. a

The use of automatic means for timing the period of oscillation of an oscillating member.

The useof such powerful resilient means for oscillating asport implement that the shaft of the sport implement whips similarly to the manner Iin which it whips in play.

` ,Theuse of a moment of inertia testingv machine into moment of inertia units.

providedwith a measuring instrument having a dial on whichlthe moment of inertia is either read directly or read in units easily convertible 'Ihe use of a scientifically determined center of oscillation for dynamically testing golf clubs and partly in'section,

'ein Fig'. 1.

Fig. 2 isa topplan View of the apparatus shown Fig. 3 is a fragmentary end view of the apparatus'showing the lclamping means.

Fig.. 4. is fa wiring diagram.

Before describing theY present improvements and mode `of operation thereof in detail it should be understood that the invention is not limited to the details of construction and arrangement oiparts shownin theaccompanying drawings, which are merely illustrative of the present preferred embodiments, since the invention is .capable of other embodiments, and the phraseology employed is; for the purpose of description and not of limitation.

The present preferred form of the invention, shown inFigs. 1 and 2, includes a horizontally disposed holder ID in the form of a metal tube. There .is provided a vertically extending plate II `having .a Vcentrally disposed flange I2 having a hole adapted .to receive the holder I0, which is held inplace yby means of -set screws I3. At both the top and bottom of the plate I lthereare aflixed mounting blocks I4 provided with machinedl surfaces I6 disposed angularly to each `lli of the mounting blocks I4, as by .means .of

screws i8 and are also attached by means of screws l to machinedgsurfacesfl! Iof mounting `blocks 2 I attached to an'uprigh't 22 lmounted upon a base 23. The projection of the springs upon the base is a cross, and the spring mounting 'as-1' sembly can suitably be called, a; flat knife edge.

spring mounting.

In the operation of the'testing machine, the'l forward portion 24 of the holder l0 can be moved to a strained position, and then suddenly released from the strained position, thereby caus ing the holder to rapidly oscillate underthe in-y uence of the resilient means consisting of the springs l1. Because the springs are fiat, 4and mounted both above and below the holder,v the placing of .weightin the holder does not cause the forward end of the holder to lower, appreciably. The projection of the springs upon the base is a cross,vand the geometric axis of the4 oscillation of thev holder ,approximately coincides with the .vertical line defined .by the intersection of the lines ofthe cross.

The holder is provided with a rear clamp 25v "lease the holder vThere is provided. a panel 50 which may be a Y Aupon the standard 41.

Near the forward end of the base 23 there is pro- Lvided a-standard 41 on whichis mounted an electro-magnet 48`-y adapted to maintain the holder and golf club in a strained position.

" In the operation of the holding means, the holder ID is manually moved toward the electromagnet 48 which, when energized, operates to maintain rthe holder in the strained position.

The testing machine is preferably provided with releasing means adapted to suddenly re- I0 from a strained position.

separate unit, or, as shown, may be mounted Upon the panel 50 is mounted a singlepole single-throw switch 5| preferably of .the push button type having a push button 52. The switchf5l is associated with the Yelectro-magnet 4B so thatwhen `the push` button 52 is depressed, the yelectro-magnetis energized, and whenrthe push button is released, the

electro-magnet is de-energized and the holder is suddenly released from its strained positionand consisting of a crotch member 26 having a 'notch Y 21 in which-a golf clubA or the like 'may be placed and held inv position by means of. a strip 29, the rear portion of which is yieldingly disposed toward the angular notch 21 of the crotch member 26 by means of a spring 30, and the forward portion of which is adjustably attached to the holder with a` thumb screw'3l. f

In the operation -of the rearclamp 25 the golf club A is slipped in the notch 21 and, heldin place by means of the spring 30 and strip29 as shown in Fig. 1. v g m The holder |0is provided with la frontclamp 32 comprising a crotchfmember .33 attached to the holder with screws 34, said crotch member 33 l clamping memberl 36 ispivoted. Withinl the handle 40 and between an.' adjusting bolt 43 and a pressure pin 44 is a'fspring 45. adapted to urge the pressure pin 44 against the clamping member 36 and to thereby cause thel clamping member to grip the, golf club A with an4 increased force. The ,handle i'svbifurcated .to Vprovide a slot 46 permitting the'handle to swing `over the clamping member and' permitting the handle to straddle the ange of the crotch member.

In the operation of the from; clamp 32 the go1f club A, or the like, is placed in the notch k of the crotch member 33 and the vclamping member 36 is swung downwardly about the pintle 38 and into the position shown in Fig.` 3, yso that the notches, 35 and Y*39 cooperatively. hold the golf club in position. Iihe handlemember 40 is'then swung upwardly ,about the pin 4I and over the clamping member 36 and 4into the position shown in Fig'. 3 so that the spring45v operatesvto urge the pressure pin 44vagainst the 'clamping member to provide increased forcejfor gripping the golf club.`I

Although 'the golf club A and holderV I0 may be held in a strained position manually, the testing machineis preferably providedwith means for allowed to oscillate underthe influence of the springs l1.

There is provided an intermittent switch`53 such as a single make contact spring switch which is usually open. The switch 53 may be lconveniently mounted in such a manner that it is closed whenever the oscillating holder I0 is in the extreme position onone side and so .that it is reopened when the' holder, in itsreturn from the extreme position to the center .position passes a I predetermined 'slightly ofcenter position. In

' the form illustrated in Fig. 2 a conventional contact spring switchv53 isrmounted upon a switch standard 54 afixed to the base 23` in an off-center 1 position, and thejholder is provided with aber projection v55 adaptedto function,v as a push pin in cooperationv with the contact springs to close the switch each time the holder, in'its oscillaltions, moves outwardly from 4the center position and pasta predetermined off-center position,

' vand tokeepthe switch vclosed while theV holder "moves to and from the extreme position, and to re-open the switch asl the holder passes the predetermined slightly off-center position during its movement toward center position. A kcondenser f 56'and high resistance element 51 may .be mount- I' ed wherever convenient, as for example, and as yshown in the drawingupon the ,switch standard 54. The resistanceeleinent 51 and condenser 55 are electricallyshunted across the switch.

Mounted upon the base 23V is a stop watch 60, suitably an electric stop watch, such as Model lS-l manufacturedby the Standard Electric Time Co. A vdial 6| of thestop watch 60 is preferably but' not necessarily marked 01T according to units of moment of inertia, and calibrated with the diall reading for the holder I0 marked as zero, so that the dial reading shows in moment-of-inertia units the measured moment of inertia of the object being tested. The stop watch is provided with an electric clutch 62Jassociated 'maintaining the holder in a` strained position. 75

with a continuously running synchronous motor 63 connected across a source of A. C.

Counting mechanism 64 such as a stepping switch, and for example, model 0023- L manufactured by the S. H. Couch Co., Norfolk Downs, Massachusetts, is mounted upon the base 23.

An electro-magnet 66 is mounted upon a frame 61. Associated with the electro-magnet 66 is an armature 68 having at one end a pawl 69 adapted to engage a ratchet gear 10 mounted on a shaft 1l passing through the frame 61 of the counting mechanism 64. The ratchet gear 10 may have,

for example, 108` teeth 'so that the shaft 1I and aflixed parts rotate 31/3 degreesv per step. Av coil spring 65 is associated with the shaft 1I`so asto return the ratchet gear 'I0 to its 'starting position whenever a detentA 12 is released.

Positioned on the opposite 4side of the frame E1 mounted for rotation with the shaft 1I is a Bakelite disc 13 having a brass segment 14 constituting 246% degrees of the circumference of the Bakelite disc 13'. Mountedv on and electrically insulated from the frame 61 is a brush 15 positioned 81/3 `degrees from one end of the segment 14. Positioned 180 degrees from the brush 15 or in other words diametrically across the Bakelite disc from the brush 15, is a -second brush 15 mounted upon and electrically insulated from the frame 61. The disc 13, segment 14, and brushes 15 and 16 constitute a timing switch 111.

A control switch 18 may suitably but not `necessarily be used, which control switch 18 `may be attached to and electrically insulated from the frame 61 and positioned behind the brushes 'I5 and 16. Mounted upon and for rotation with the shaft 1I is a cam 19 adapted to open the normally closed contact spring control switch` 18 at the same time, or within a few steps after, segment 14 breaks electrical connection-with the brush 16 to open the timing-switch 11.

In the operation of the timing switch 11 the electro-magnet 66 is `intermittently energized, thereby intermittently attracting theV armature B8, thereby actuating the pawl 69, hereby rotating the ratchet gear a step at a time'. (The segment 14 mounted upon the Bakelite disc 13 v afxed to the shaft 1Ifor rotation withl the ratchet gear 10 advances 81/3 degrees to thereby form an electrical connection between the oppositely disposed brushes and 16, ftherebyclosing the timing switch 11. After twenty additional impulses have caused the ratchet gear-13 to rotate 662/3 degrees additional'lyi'the brush 16 is electrically disconnected from the segment 14, thereby opening the timing` switch 11. The counting mechanism 64 can be returned toithe normal starting position bymanually releasing the detent 12. l i i l i In the operation of the control switch 18, the electro-magnet 56 causes the shaft 1I tojrotate step-by-step untilthe timing switch 11 .re-opens,

at which time or within a few steps thereafter,

the cam 19 causes the normally closed contact spring switch 18 toopen. l

In Fig.` 4 i-s shown` a wiring diagram of the testing machine. Direct current source D, 0.50perates the electro-magnet 48 ,to maintain the lholder It in a strained position until the push button of the switch 5I is released, at which'time the holder startsoscillating. The intermittent circuit is closed by the oscillations of the 4holder actuating the intermittentswitch 53. A condenser 56 and a high resistance element 51 are shunted across the intermittent switch 53 toY prevent the contacts from sparking. Each time the intermittent switch 53 is closed, the electromagnet 66 is energized, and the pawl 69 Vrotates the ratchet gear 10 and associated elements a unitary amount. After two and one-half oscillations, the timing vswitch 11 i-s closed by the brass segment 14 touching both of the brushes l'and 16 thereby energizing the clutchmagnet 62 rto initiate the operation of the stop watch 61.1.

After the stop -watch' has operated 'during twenty oscillations of the holder-II) `the timing switch 11 is opened and concurrently thecam 19 causes the control switch 1.8 to ,open so that additional oscillations of the holder I0 will not unduly advance the counting mechanism 64.

switch 11 during an individual test, the `control switch 18 needv not be used. If the operator manually stops the oscillations of the holder I0 after the stop-watch 60 has stopped, the control switch 18 need not be used. If the `springs I1 have Ysuitable characteristics, the timing switch 11 may be closed after fewer than two and one-half oscillations of the holder, the purpose of the switching being to provide an accurate timing of the rperiod of oscillation, free from errors due to starting or stopping transients. If the springs I1 have suitable characteristics, `the moment of inertia of a golf club as determined by the testing machine will be exactly the same as the mo ment of inertia determined by any other accu- -rate scientific method. However, `if the springs are powerful enough to cause the golf club shaft to whip, thenl the Iproperty measuredby the testing machine is related to and somewhatdependent uponbut not exactly equal to, the moment .of inertia.

determining the proper strength ofsprings for a given machine, it is possible to obtain a substantially perfect accuracy. When a group of clubs is tested upon such a machine, the relative feel factors thus determined by the testing vmachine are substantially identical with the ap.- praisal of the feel factors of that group of clubs by typical golfers. There have been many golf club testing machines, but it has not heretofore been possible to use amachine for testing golf clubs to produce the identical appraisal achieved by players testing and using the clubs.

In the development of one testing machine, it was found that when the empty holder I0 was allowed to oscillate for twenty oscillations, the stop watch 60 recorded 4.21 seconds, which corresponded to a moment of inertia of `approximately 350 pounds-inches squared. It was found that when a golf club was placed in the holder and tested, the stop watch ordinarily recorded from 6.70 to '1.10` seconds, corresponding to amoment of inertia for the golf club of from about l1020 pounds-inches squared to about 1145 poundsinches squared. It was found that the moment of inertia of the Vobject being tested could be read directly from the dial of the stop watch by markink off the dial of the stop watch in units of pounds-inchessquared, and by setting the point i corresponding to the moment of inertia of the 'golf-club testing' methods heretofore proposed have utilized the testing of balance about a point on the golf club shaft one or,y two inches from the An important point, and one leading to-great accuracy with the present process and apparatus, consists of fixing the center aboutwhich the moment is to be determined by a scientific procedure instead of by guess.

It has been found that the instantaneous center for the movement of a golf club may be determined from geometric calculations involving multiashy photographs of a golf club swing. We have'found that over short sections of the swing Athe path is reasonably close to being circular. Therefore, instead of drawing tangents to the path 'of the club We assume that the chord between two points is parallel to the tangent that would be drawn to a mid-point on the actual path between the two points. Thus we draw chords to two pairs of vpoints on the golf clubs and erect perpendicular bisectors to the chords. The intersection of the two perpendicular bisectors is the mean instantaneous center of the two'club positions used.

By' extensive research-and with the aid of multi-dash pictures of such golf experts as Bobby Jones, during a typical swing or stroke, it has been found that the instantaneous center during the golf club swing is generally at a point beyond the upper end of the golf club shaft, and that its exact location varies as the club is swung. At the instant when the club hits the ball, or, in other words, when the club has the greatest power, and therefore is most sensitive to relative imperfections in physical properties related to moment of inertia, the instantaneous center of the club may be from 1A; of an inch to 21/2 inches beyond the end of the club shaft, depending upon the individual player and other variables. Determining the average instantaneous center during the greatest time interval of the club swing resulted in approximately the same values.

It has been found thatfa reasonably accurate appraisal of the instantaneous center vwhich govf erns the feel of a golf club is approximately 1% inches beyond the end of the golf club shaft, but as pointed out heretofore, it may be from 1/8 to 21/2 inches without developing excessive inaccuracy. Forv clubs other than golf, multiflash-f photos might show that the scientic determination of the correct instantaneous center was on the club shaft instead of on the extension thereof. The holder'lis adjustable with respect to the plate Il for oscillation' about a point cna"- playing implement shaft. v

' In the operation of the machine, a golf club is placed in the holder I and the handle 40 is raised over the clamping member 32. The push button 52 is depressed and the holder moved toward the energized electro-magnet 48. The detent 12 is released to allow the counting mechanism 64 to return to the starting position. The push button 52 is released and the holder |0 al lowed to oscillate. the hand of the stop watch 60 points out the feel factor of the golf club. The stop watch may be returned to the starting position, and the golf club removed from the holder, and another golf club tested as above described. A skilled operator can test a large number of golf clubs per hour by this method, especially if he operates several machines simultaneously.

Numerous variations can be made without departing from the teaching ofthe present inven- After about seven seconds;

' tion, and the description is intended as one of illustration rather than of limitation.

Having thus described the invention, what is claimed as new is:

1. In a testing apparatus the combination of a base; a holder; resilient means normally supporting said holder in a neutral position upon the base and enabling movement of said holder in opposite axial directions into opposed strained positions relative to said neutral position; and means for maintaining said holder in one of said strained positions displaced from said neutral position.

2. In a testing apparatus the combination of a base; a holder; means pivotally supporting said holder on said base for oscillatory movement; timing mechanism; counting mechanism; and electrical means associating 'said timing and counting mechanisms with each other and with said holder for timing and counting a predetermined number of oscillations of said holder.

3. In a testing apparatus the combination of a base; a holder; opposed springs pivotally'supporting said holder on said base; a counter mechanism; and means associating said counter mechanism With said holder.

4. In a testing apparatus the combination of a base; a. holder oscillatorily supported on the base; a delayed timing and counting mechanism for timing and counting oscillations of the holder; and means associating said last-named mechanism with said holder.

5. In a testing apparatus the combination of a base; a holder; means associating the baseand holder adapted to oscillate the holder when it is lreleased from a strained position; means for maintaining said holder in the strained position; counting mechanism for indicating the number of oscillations of said holder; and consaid holder in the strained position; and means for' releasing said holding means and for concurrently initiating said counting mechanism.

7. In a testing apparatus the combination of a base; e. holder; means associating said holder and said base adapted to oscillate the holder when released from a strained position; `electrical counter mechanism for counting oscillations of said holder; electrical timing mechanism for timing a predetermined number of oscillations; elec- Ya base; a holder; resilient means oscillatorily supporting said holder on said base; mechanism for counting the oscillations of the holder; timing mechanism; and means controlled by the counting mechanism for initiating the timing at a predetermined period in the oscillation of the holder.

10. In a testing apparatus the combination of a base; a holder; resilient means oscillatorily supporting said holder on said base; mechanismV for counting the oscillations of the holder; timing mechanism; means controlled by the counting mechanism for initiating the timing means at a predetermined period in the oscillation of the holder; and means for maintaining said holder in a strained position.

11. In va'testing apparatus the combination of a base; a holder; resilient means oscillatorily supporting said holder on said base; counting mechanism actuated upon oscillation of said support; timing mechanism; and electrical means for concurrently initiating the timing and counting means at a predeterminedperiod in the oscillation of the holder.

12. In a testing apparatus the combination of a base; a holder; means associating said base and said holder adapted to oscillate the holder when it is released from a strained position; counting mechanism for counting oscillations of said holder; timing mechanism forr timing a predetermined number of oscillations; and means for starting and stopping said timing and counting mechanisms at predetermined periods in the oscillation of said holder.

13. A machine for testing the feel factor of a sport implement comprising a sport implement holder; resilient; means oscillatorily supporting the holder; an electrical measuring means; and l means associating the electrical measuring means and the holder so that the electrical measuring means is responsive to the nature of the oscillations of the holder.

14. A sport implement testing machine comprising a holder; means associated with said holder and adapted to oscillate the holder when released from a strained position; measuringT means; and means associating the oscillating holder and measuring means, controlled by oscillation of said holder and adapted to operate the measuring means only during a predetermined group of oscillations.

15. In a testing machine the combination of a rst electrical circuit including a source of electrical energy, an electrical measuring means having an indicator, and switching means adapted to operate the measuring means only when closed; a second electrical circuit including another source of electrical energy, an intermittent switch actuated incident to the test adapted to intermittently pass electrical impulses, and an electromagnetic device actuated by said intermittent impulses; and means associating said electromagnetic device and the measuring means switching means to close the first circuit after a predetermined number of electrical impulses, and to open said circuit after an additional predetermined number of said impulses to indicate directly on the electrical measuring means the result of the test.

16. In a testing apparatus the combination of a base; a holder; resilient means oscillatorily supporting said holder on said base for oscillatory movement relative to an axis of oscillation; means enabling adjustment of said holder transversely relative to said axis of oscillation; counting mechanism for counting oscillations of said holder; and means associating said counter mechanism and said holder.

17. The process of testing implements having flexible shafts to determine the dynamic movement of inertia thereof which includes the steps of oscillatorily supporting said shaft adjacent one` end therecf, forcibly deliecting the other end and releasing the same for oscillating said implement; simultaneously starting a timing and an oscillation counting operation after a stabilized oscillatory condition is established; stopping the counting operation at a predetermined total; and determining the time interval for said counting operation.

18. The process of measuring the moment of inertia of a golf club or the like having a flexible shaft consisting of supporting the club by the end of the shaft in a holder of which the moment of inertia and period of oscillation are known; oscillating the holder and club; initiating a timing operation after a predetermined number of oscillations, to thereby avoid inaccuracies incident to starting transients; immediately stopping the timing operation after an additional predetermined number of oscillations; and determining the index of the moment of inertia of the club from the time interval during the timing operation.

19. The process of testing implements having a flexible shaft to determine the dynamic moment of inertia of said implement, the steps of supporting the shaft adjacent one end, forcibly deiiecting the free end of the shaft and releasing the same to set up oscillations therein, the initial oscillations being utilized to stabilize the oscillatory condition; and simultaneously counting and timing' said oscillations through a succeeding predetermined period. l

20. The process of testing implements having a flexible shaft to determine the moment of inertia of said implement, the steps of supporting the shaft adjacent one end, forcibly deflecting the free end of the shaft and releasing the same to set up oscillations therein, the initial predetermined number of oscillations being untimed; and subsequently timing a predetermined number of oscillations.

21. The method of testing and matching a set of Vgolf clubs of different types each having a exible shaft, the steps of individually oscillatorily supporting a plurality of clubs of the different types adjacent one end of the shaft; applying a similar force to the free end of each of the shafts to deflect the same; releasing said shafts to set up oscillations therein, the initial predetermined number of oscillations being untimed to provide a stable condition of oscillation; timinglr a predetermined number of subsequent oscillations to provide an index; and selecting a club of each type having the same index whereby a matched set of clubs having the same feel is obtained.

Y MAX KNOBEL.

JOI-IN B. DICKSON. JOHN W. BAYMILLER. 

